Inhibition of SUMO-1 Expression by LH Receptor Stimulation is Linked to Induction of Progesterone Receptor During Ovulation in Mouse Granulosa Cells
Shao R, et al .
The small ubiquitin-related modifier-1 (SUMO-1) is a member of a family of ubiquitin-related proteins which have effects on several important physiological functions, including reproduction. However, the regulation of SUMO-1 expression and functional distribution of SUMO-1 in vivo remain poorly understood. SUMO-1 protein is widely expressed in various tissues. In the ovary, the expression of SUMO-1 protein is suppressed around ovulation in both the whole ovary and the granulosa cells after gonadotropin treatment. Additionally, when the ovulatory signal, the endogenous LH surge, is blocked in vivo by pentobarbitone sodium, the expression of SUMO-1 protein in granulosa cells is increased. This effect is reversed when the missing endogenous LH surge is substituted by hCG treatment. The findings provide the first evidence that inhibition of SUMO-1 expression is regulated by LH receptor stimulation in granulosa cells concomitant with ovulation in the mouse ovary. Furthermore, the levels of SUMO-1 protein are increased in granulosa cells treated with PR antagonists both in vivo and in vitro, demonstrating that SUMO-1 expression is regulated by functional PR. SUMO-1 interacts with nuclear receptors in vitro and LH receptor-mediated induction of progesterone receptor (PR) is crucial for ovulation. SUMO-1 and PR are co-expressed and can be co-precipitated, providing additional evidence for a direct interaction between SUMO-1 and PR in periovulatory granulosa cells in vivo. These results suggest that a functional link between SUMO-1 and PR is of physiological importance for the local modulation of progesterone receptor-mediated events in the ovary.
NCBI Summary:
This gene encodes a protein that is a member of the SUMO (small ubiquitin-like modifier) protein family. It functions in a manner similar to ubiquitin in that it is bound to target proteins as part of a post-translational modification system. However, unlike ubiquitin which targets proteins for degradation, this protein is involved in a variety of cellular processes, such as nuclear transport, transcriptional regulation, apoptosis, and protein stability. It is not active until the last four amino acids of the carboxy-terminus have been cleaved off. Several pseudogenes have been reported for this gene. Alternate transcriptional splice variants encoding different isoforms have been characterized. [provided by RefSeq, Jul 2008]
General function
Cell cycle regulation
Comment
Cellular localization
Nuclear
Comment
Identifying susceptibility genes for primary ovarian insufficiency on the high-risk genetic background of a fragile X premutation. Trevino CE et al. (2021) To identify modifying genes that explains the risk of fragile X-associated primary ovarian insufficiency (FXPOI). Gene-based, case/control association study, followed by a functional screen of highly ranked genes using a Drosophila model. Participants were recruited from academic and clinical settings. Women with a premutation (PM) who experienced FXPOI at the age of 35 years or younger (n = 63) and women with a PM who experienced menopause at the age of 50 years or older (n = 51) provided clinical information and a deoxyribonucleic acid sample for whole genome sequencing. The functional screen was on the basis of Drosophila TRiP lines. Clinical information and a DNA sample were collected for whole genome sequencing. A polygenic risk score derived from common variants associated with natural age at menopause was calculated and associated with the risk of FXPOI. Genes associated with the risk of FXPOI were identified on the basis of the P-value from gene-based association test and an altered level of fecundity when knocked down in the Drosophila PM model. The polygenic risk score on the basis of common variants associated with natural age at menopause explained approximately 8% of the variance in the risk of FXPOI. Further, SUMO1 and KRR1 were identified as possible modifying genes associated with the risk of FXPOI on the basis of an untargeted gene analysis of rare variants. In addition to the large genetic effect of a PM on ovarian function, the additive effects of common variants associated with natural age at menopause and the effect of rare modifying variants appear to play a role in FXPOI risk.//////////////////
Ovarian function
Ovulation, Oocyte maturation
Comment
SUMO-1 plays crucial roles for spindle organization, chromosome congression, and chromosome segregation during mouse oocyte meiotic maturation. Yuan YF 2014 et al.
Small ubiquitin-related modifier-1 (SUMO-1)-dependent modifications of many target proteins are involved in a range of intracellular processes. Previous studies reported the localization of SUMO-1 during oocyte meiosis, and that overexpression of Sentrin/SUMO-specific protease 2 (SENP2), a de-SUMOylation protease, altered SUMO-modified proteins, and caused defects in metaphase-II spindle organization. In this study, we detailed the consequences of SUMO-1-mediated SUMOylation by either inhibition of SUMO-1 or UBC9 with a specific antibody or their depletion by specific siRNA microinjection. Inhibition or depletion of SUMO-1 or UBC9 in germinal vesicle (GV)-stage oocytes decreased the rates of germinal vesicle breakdown and first polar body (PB1) extrusion; caused defective spindle organization and misaligned chromosomes; and led to aneuploidy in matured oocytes. Stage-specific antibody injections suggested that SUMO-1 functions before anaphase I during PB1 extrusion. Further experiments indicated that the localization of ?-tubulin was disordered after SUMO-1 inhibition, and that SUMO-1 depletion disrupted kinetochore-microtubule attachment at metaphase I. Moreover, SUMO-1 inhibition resulted in less-condensed chromosomes, altered localization of REC8 and securin, and reduced BUBR1 accumulation at the centromere. On the other hand, overexpression of SUMO-1 in GV-stage oocytes had no significant effect on oocyte maturation. In conclusion, our results implied that SUMO-1 plays crucial roles during oocyte meiotic maturation, specifically involving spindle assembly and chromosome behavior, by regulating kinetochore-microtubule attachment and the localization of ?-tubulin, BUBR1, REC8, and securin. Mol. Reprod. Dev. 81: 712-724, 2014. ? 2014 Wiley Periodicals, Inc.
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The SUMO pathway functions in mouse oocyte maturation. Wang ZB et al. Sumoylation is an important posttranslational modification in which SUMO (small ubiquitin-related modifier) proteins are bonded covalently to their substrates. Studies on the roles of sumoylation in cell cycle regulation have been emerging in both mitosis from yeast to mammals and meiosis in budding yeast, but the functions of sumoylation in mammalian meiosis, especially in oocyte meiotic maturation are not well known. Here, we examined the localization and expression of SUMO-1 and SUMO-2/3, the two basic proteins in the sumoylation pathway and investigated their roles through overexpression of Senp2 during mouse oocyte maturation. Immunofluorescent staining revealed differential patterns of SUMO-1 and SUMO-2/3 localization: SUMO-1 was localized to the spindle poles in prometaphase I, MI and MII stages, around the separating homologues in anaphase I and telophase I stages of first meiosis, while SUMO-2/3 was mainly concentrated near centromeres during mouse oocyte maturation. Immunoblot analysis uncovered the different expression profiles of SUMO-1 and SUMO-2/3 modified proteins during mouse oocyte maturation. Overexpression of Senp2, a SUMO-specific isopeptidase, caused changes of SUMO-modified proteins and led to defects in MII spindle organization in mature eggs. These results suggest that the SUMO pathway may play an indispensable role during mouse oocyte meiotic maturation.
Expression regulated by
LH
Comment
Ovarian localization
Oocyte, Granulosa
Comment
Induction of apoptosis increases SUMO-1 protein expression and conjugation in mouse periovulatory granulosa cells in vitro Shao R, et al .
The small ubiquitin-related modifier-1 (SUMO-1) with broad cellular expression has been implicated in a range of cellular processes, such as cell proliferation, differentiation, and apoptosis. As shown recently, SUMO-1 is expressed and regulated by gonadotropins, in particular an ovulatory hCG stimulus in mouse granulosa cells in vivo. To test the hypothesis that modulation of granulosa cell apoptosis changes SUMO-1 expression during granulosa cell differentiation in the mouse ovary, we demonstrate that progesterone receptor (PR) proteins are absent in pre-ovulatory granulosa cell nuclei, whereas they are expressed in periovulatory granulosa cell nuclei in parallel with decreases in SUMO-1 expression, caspase-3 activation, and DNA fragmentation in vivo. Second, treatment with either PR antagonists or a cell permeable ceramide analog consistently increases SUMO-1 expression in parallel with an increase in apoptosis as well as a decrease in cell proliferation in periovulatory granulosa cells in vitro. However, we do not observe an increase in SUMO-1 expression in pre-ovulatory granulosa cells that have undergone the same treatment. Third, we have also demonstrated, in pre-ovulatory granulosa cells in vitro, neither induction of spontaneous apoptosis nor the protective effect of EGF against spontaneous apoptosis changes SUMO-1 protein expression. Fourth, we show that induction of apoptosis enhances SUMO-1 conjugation in periovulatory granulosa cells in vitro, pointing to the pivotal link between the SUMO-1 conjugation and cell death. Taken together, our observations suggest that SUMO-1 via sumoylation has an important role in the regulation of granulosa cell apoptosis during granulosa cell differentiation in the mouse ovary.
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